A self-microporous polymer and its preparation method and application

Abstract

The present invention relates to the technical field of gas membrane separation, and in particular to a self-microporous polymer and its preparation method and application. The present invention obtains a self-microporous polymer by mixing an indole diquinol monomer with tetrafluoroterephthalonitrile, an alkali catalyst, a solvent and a water-carrying agent. The structural formula of the indole diquinol monomer is shown in Formula I; #imgabs0# The self-microporous polymer has a structural formula shown in Formula II; #imgabs1# In Formula I and Formula II, R is #imgabs2#‑CH3 or ‑Ph‑C(CH3)3; n is the degree of polymerization, and n is an integer, preferably n is an integer of 1 to 100. The film prepared by using the self-microporous polymer of the present invention has the characteristics of high gas selectivity, high permeability, good solubility and good selectivity, and has excellent thermal properties. It can be used as a new self-microporous polymer gas separation membrane and has broad application prospects in the field of gas membrane separation membranes.

Description

Technical Field

[0001] The invention relates to the technical field of gas membrane separation, in particular to a self-microporous polymer and a preparation method and application thereof. Background Art

[0002] Membrane separation technology is an emerging technology with the greatest development potential since the 21st century. Compared with traditional separation methods, it has the advantages of high efficiency, environmental protection, simple and flexible operation, etc. It is widely used in the separation of gases such as natural gas, hydrogen, nitrogen, oxygen and carbon dioxide. In the selection of membrane separation materials, self-microporous polymers inhibit the free rotation of chain conformations in space by constructing polymer chains that combine rigidity and twisted structures. The introduction of twisted structures makes it difficult for polymer chains to be stacked regularly in space, resulting in cavities or large free volumes. Compared with three-dimensional skeleton porous materials, self-microporous polymers have both high specific surface area and processability, making them have significant applications in membrane separation, catalysis and other fields and have attracted much attention.

[0003] The first self-microporous polymer (PIM-1) was reported by McKeown and Budd in 2004. It was synthesized by polymerization of 2,3,5,6-tetrafluoroterephthalic acid ethylenenitrile and spirocyclic 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspiroindan. The interconnected micropores inside the membrane can make the gas separation performance of self-microporous polymer membranes break through the limitations between gas permeability and selectivity of traditional polymer membranes (i.e., Robeson upper limit), so more and more research is being done on self-microporous polymers. Since then, countless researchers have used different twisted groups for structural design and synthesis of self-microporous polymers. These rigid and twisted units can effectively avoid conformational changes. Through nearly two decades of development and innovation, there are now hundreds of self-microporous polymers.

[0004] According to their connection structure, self-microporous polymers can be divided into three categories: 1) ladder-shaped self-microporous polymers, such as PIM-1 and Base polymers with inherent micropores; 2) Linear PIMs, such as polyimide, polybenzimidazole, and polyether-ether ketone; 3) Hyper-crosslinked polymers with inherent micropores, such as polymers containing phthalocyanine. Studies have shown that by changing the structure or functional groups of the main chain structural units and side chains, the stacking of polymer chains can be adjusted and their porosity can be controlled, thereby fine-tuning the gas separation performance. According to previous reports, researchers have used various twisted structure monomers to produce micropores, such as tris-discene, Base (TB), tetraphenylethylene, helioxane, spirofluorene, ethane anthracene and norbornene cyclization (CANAL). The development of new rigid and twisted linking units to tune gas separation performance has attracted the attention of many researchers. However, so far, the use of indole building blocks in the twisted structures of many synthetic PIMs has rarely been reported. Summary of the invention

[0005] Based on the above content, the present invention provides a self-microporous polymer and a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is an indole diquinol monomer, the structural formula of which is shown in Formula I;

[0008]

[0009] In formula I, R is -CH3 or -Ph-C(CH3)3.

[0010] The second technical solution of the present invention is a method for preparing the above-mentioned indole diquinol monomer, comprising the following steps:

[0011] Step 1, subjecting indoledione and o-phthalic acid to a Friedel-Crafts acylation reaction to obtain an indole diphenyl tetramethyl ether monomer;

[0012] Step 2, subjecting the indole diphenyl tetramethyl ether monomer to an N-alkyl substitution reaction with a halogenated compound to obtain an indole diphenyl tetramethyl ether monomer containing different side groups;

[0013] Step 3: subjecting the indole diphenyl tetramethyl ether monomer containing different side groups to a Lewis acid catalyst for a Lewis acid-catalyzed reaction to obtain the indole diphenyl tetramethyl ether monomer.

[0014] The third technical solution of the present invention is the application of the above-mentioned indole diquinol monomer in the preparation of self-microporous polymers or membrane separation fields.

[0015] A fourth technical solution of the present invention is a self-microporous polymer, the structural formula of which is shown in Formula II;

[0016]

[0017] In formula II, R is -CH3 or -Ph-C(CH3)3; n is the degree of polymerization, and n is an integer; preferably, n is an integer of 1 to 100.

[0018] A fifth technical solution of the present invention is a method for preparing the above-mentioned self-microporous polymer, comprising the following steps:

[0019] The above-mentioned indole diquinol monomer is mixed with tetrafluoroterephthalonitrile, an alkali catalyst, a solvent and a water-carrying agent to react and obtain the self-microporous polymer.

[0020] The sixth technical solution of the present invention is a gas separation membrane, the raw materials of which include the above-mentioned self-microporous polymer.

[0021] The present invention discloses the following technical effects:

[0022] 1) The present invention provides a tetraphenol monomer containing an indole structure substituted with different side groups (indole diphenyl tetraphenol monomer), wherein the tetraphenol monomer containing an indole structure substituted with different side groups is obtained by introducing the indole structure substituted with different side groups into the tetraphenol monomer.

[0023] 2) The tetraphenol monomer containing indole structures substituted with different side groups (indole diphenyl tetraphenol monomer) of the present invention can undergo a nucleophilic substitution reaction with tetrafluoroterephthalonitrile in a non-protonic polar solvent under the action of an alkali catalyst to prepare a series of self-microporous polymers containing indole spiro structures with different side groups.

[0024] 3) The film prepared by using the self-microporous polymer with indole spiro ring structure containing different side groups of the present invention has a self-microporous structure, and the introduction of the spiro ring center containing different side groups and indole structure increases the non-coplanarity of the self-microporous polymer, which can improve the gas permeability. The introduction of different side groups increases the microporosity and rigidity of the polymer film, further improving the gas permeability.

[0025] 4) The film prepared by using the self-microporous polymer of the present invention has the characteristics of high gas selectivity, high permeability, good solubility and good selectivity, and also has excellent thermal properties. It can be used as a new self-microporous polymer gas separation membrane and has broad application prospects in the field of gas membrane separation membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is the infrared spectrum of the indole diquinol monomer containing benzonitrile side groups prepared in Example 1 of the present invention.

[0028] Figure 2 This is the NMR spectrum of the indole diquinol monomer containing benzonitrile side groups prepared in Example 1 of the present invention.

[0029] Figure 3 This is the infrared spectrum of the self-microporous polymer with indole spiro structure containing benzonitrile side groups prepared in Example 2 of the present invention.

[0030] Figure 4 This is the infrared spectrum of the indole diquinol monomer containing methyl side groups prepared in Example 3 of the present invention.

[0031] Figure 5 This is the NMR spectrum of the indole diquinol monomer containing methyl side groups prepared in Example 3 of the present invention.

[0032] Figure 6 This is the infrared spectrum of the self-microporous polymer with indole spiro structure containing methyl side groups prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0037] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0038] The first aspect of the present invention provides an indole diquinol monomer, the structural formula of which is shown in Formula I;

[0039]

[0040] In formula I, R is -CH3 or -Ph-C(CH3)3.

[0041] The IUPAC name of the indole diquinol monomer is: 3,3'-bis(3,4-dihydroxyphenyl)indol-2-one.

[0042] The second aspect of the present invention provides a method for preparing the above-mentioned indole diquinol monomer, comprising the following steps:

[0043] Step 1, subjecting indoledione and o-phenyl dimethyl ether to a Friedel-Crafts acylation reaction to obtain an indole diphenyl tetramethyl ether monomer; the reaction formula is as follows:

[0044]

[0045] Step 2, subjecting the indole diphenyl tetramethyl ether monomer to an N-alkyl substitution reaction with a halogenated compound to obtain an indole diphenyl tetramethyl ether monomer containing different side groups; the reaction formula is as follows:

[0046]

[0047] Step 3, subjecting the indole diphenyl tetramethyl ether monomer containing different side groups to a Lewis acid catalyst for a Lewis acid-catalyzed reaction to obtain the indole diphenyl tetramethyl ether monomer; the reaction formula is as follows:

[0048]

[0049] In the above reaction formula, R is -CH3 or -Ph-C(CH3)3.

[0050] In some embodiments of the present invention, in step 1, the molar ratio of the indoledione to the o-phenylenedimethyl ether is 1:3; the temperature of the Friedel-Crafts acylation reaction is 110-120° C., and the time is 4-5 h.

[0051] An acidic catalyst is also added during the Friedel-Crafts acylation reaction; the acidic catalyst is at least one of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid and trifluoromethanesulfonic acid; after the Friedel-Crafts acylation reaction is completed, the process further includes pouring the product obtained from the Friedel-Crafts acylation reaction into water and filtering, washing and drying in sequence.

[0052] In some embodiments of the present invention, in step 2, the molar ratio of the indole diphenyl tetramethyl ether monomer to the halogenated compound is 1:(1-2.5); the halogenated compound is one of p-fluorobenzonitrile, p-chlorobenzonitrile, methyl iodide and tert-butyl bromobenzene; the temperature of the N-alkyl substitution reaction is 100-120°C, and the time is 14-30h.

[0053] A catalyst is also added during the N-alkyl substitution reaction; the catalyst is an alkali metal or an alkali metal salt; the catalyst is potassium carbonate, cesium carbonate or calcium hydride; the solvent of the N-alkyl substitution reaction is N,N-dimethylformamide; after the N-alkyl substitution reaction is completed, the steps of pouring the product obtained by the N-alkyl substitution reaction into water and filtering, washing and drying in sequence are also included.

[0054] In some embodiments of the present invention, in step 3, the molar ratio of the indole diphenyl tetramethyl ether monomer containing different side groups to the Lewis acid catalyst is 1:(10-15); the Lewis acid catalyst is boron bromide or aluminum trichloride; the temperature of the Lewis acid-catalyzed reaction is 0°C and the time is 10h-24h.

[0055] The solvent of the Lewis acid catalytic reaction is dichloromethane. After the Lewis acid catalytic reaction is completed, the steps of pouring the product obtained by the Lewis acid catalytic reaction into water and filtering, washing and drying in sequence are also included.

[0056] The Friedel-Crafts acylation reaction, N-alkyl substitution reaction and Lewis acid catalysis reaction are all carried out under a nitrogen atmosphere.

[0057] The preparation method of the indole diquinol monomer of the present invention has not only simple process, mild reaction and easy control, but also easy acquisition of raw materials and reagents, low cost and easy industrial production.

[0058] The third aspect of the present invention provides an application of the above-mentioned indole diquinol monomer in the field of preparing self-microporous polymers or membrane separation.

[0059] The fourth aspect of the present invention provides a self-microporous polymer, the structural formula of which is shown in Formula II;

[0060]

[0061] In formula II, R is -CH3 or -Ph-C(CH3)3; n is the degree of polymerization, and n is an integer, preferably n is an integer of 1 to 100.

[0062] The self-microporous polymer of the present invention is a self-microporous polymer with an indole spiro ring structure containing different side groups, and is a new generation of self-microporous polymer containing a spiro ring structure, and has broad application prospects in the field of gas membrane separation.

[0063] A fifth aspect of the present invention provides a method for preparing the above-mentioned self-microporous polymer, comprising the following steps:

[0064] The above-mentioned indole diquinol monomer is mixed with tetrafluoroterephthalonitrile, a base catalyst (base or alkali metal salt), a solvent and a water-carrying agent to react to obtain the self-microporous polymer. The reaction formula is as follows:

[0065]

[0066] In the above reaction formula, R is -CH3 or -Ph-C(CH3)3.

[0067] In the present invention, a self-microporous polymer having an indole spirocyclic structure is prepared by a nucleophilic substitution reaction of an indole diquinol monomer containing different side groups and a tetrafluoroterephthalonitrile monomer. The self-microporous polymer cannot be effectively stacked to form a microporous structure due to the rigidity of its molecular chain, and the introduction of the indole structure containing different substituents further adjusts the size of the micropores inside the polymer, and these micropores can provide channels for gases, increase the permeability of the gas to be separated, and thus play an efficient separation role. The introduction of the indole structure substituted with different side groups further adjusts the size of the micropores inside the polymer, and these micropores can provide channels for gases, increase the permeability of the gas to be separated, and thus play an efficient separation role. The self-microporous polymer gas separation membrane made of the indole diquinol monomer has high permeability, good solubility and good selectivity.

[0068] In some embodiments of the present invention, the molar ratio of the indole diquinol monomer to tetrafluoroterephthalonitrile and the base catalyst is 1:1:3; and the solvent is an aprotic polar solvent.

[0069] In some embodiments of the present invention, the reaction temperature is 130-200°C, and the reaction time is 4-30h; specifically, the temperature is raised to boiling of the water-carrying agent, that is, the temperature is raised to 100°C-150°C, and the water-carrying time is 2-8h (preferably the temperature is raised to 120°C-140°C, and the water-carrying time is 6-8h), and after the temperature is raised to boiling of the water-carrying agent, the water-carrying agent is evaporated.

[0070] In some embodiments of the present invention, the solvent is sulfolane, N-methylpyrrolidone, dimethyl sulfoxide or N,N'-dimethylacetamide; the water-carrying agent is at least one of benzene, toluene, xylene and chlorobenzene.

[0071] In some embodiments of the present invention, the amount of the solvent is 1-4 times the total mass of the indole diquinol monomer, tetrafluoroterephthalonitrile and base catalyst. The amount of the water-carrying agent is 3 times the mass of the solvent.

[0072] In some embodiments of the present invention, after the reaction is completed, the reaction material is further added to a sedimentation agent, boiled, filtered, and dried; the sedimentation agent is at least one of methanol, ethanol, and water. 100-500 mL of sedimentation agent is required for every 1 g of the self-microporous polymer.

[0073] A sixth aspect of the present invention provides a gas separation membrane, the raw material of which includes the above-mentioned self-microporous polymer.

[0074] The present invention is further described below with reference to the embodiments.

[0075] Example 1

[0076] This embodiment provides an indole diquinol monomer containing a benzonitrile side group, and the preparation method is as follows:

[0077] 1) In a nitrogen atmosphere, 14.7 g of indoledione (0.1 mol) and 42 g of o-phenyl dimethyl ether (0.3 mol) were added to a 100 mL three-necked flask equipped with a stirrer, 50 ml of sulfuric acid was slowly added under stirring, the mixture was stirred and mixed, the temperature was slowly raised to 120 ° C and heated under reflux for 5 h, the resulting mixed solution was poured into deionized water, filtered, repeatedly washed with deionized water until neutral, and dried to prepare indole diphenyl tetramethyl ether monomer.

[0078] 2) In a nitrogen atmosphere, in a 100 mL three-necked flask equipped with a stirrer, first add 8 g of the product of step 1) (0.02 mol) and 2.8 g of p-fluorobenzonitrile (0.02 mol), then add 4 g of potassium carbonate and 25 ml of N,N-dimethylformamide solvent, stir and mix, slowly heat to 120 ° C and heat under reflux for 20 h, pour the obtained mixed solution into deionized water, filter, repeatedly wash with deionized water until neutral, and dry to prepare an indole diphenyl tetramethyl ether monomer containing a benzonitrile side group.

[0079] 3) Under ice bath conditions, 0.3024 g of the product of step 2) (0.0006 mol) was added to a reaction vessel equipped with a stirrer and a condenser, 6 ml of dichloromethane solvent was slowly added under stirring, and 1.5 g of boron bromide (0.006 mol) was slowly added through a water separator. After reacting for 12 h, deionized water was added to quench the reaction. The resulting mixed solution was poured into deionized water, filtered, repeatedly washed with deionized water until neutral, and dried to prepare an indole diquinone monomer containing a benzonitrile side group.

[0080] The infrared spectrum and nuclear magnetic resonance spectrum of the indole diquinol monomer containing benzonitrile side groups prepared in this example are as follows: Figure 1 and Figure 2 shown.

[0081] Example 2

[0082] This embodiment provides a self-microporous polymer having an indole spiro ring structure and containing a benzonitrile side group, and the preparation method is as follows:

[0083] In a nitrogen atmosphere, in a 100 mL three-necked flask with a stirring rod, the indole diquinol monomer containing benzonitrile side groups prepared in Example 1, an equal molar amount of tetrafluoroterephthalonitrile and 3 times the molar amount of potassium carbonate were first added, and then 4 times the total mass of N,N-dimethylacetamide solvent and 3 times the mass of N,N-dimethylacetamide solvent were added. The mixture was stirred and mixed, and refluxed at 130° C. for 7 h. The obtained material was slowly poured into methanol for precipitation, and then boiled, filtered and dried to obtain a self-microporous polymer with an indole spiro ring structure containing benzonitrile side groups, whose number average molecular weight was 70,000.

[0084] The infrared spectrum of the self-microporous polymer with indole spiro ring structure containing benzonitrile side groups prepared in this example is as follows: Figure 3 shown.

[0085] Example 3

[0086] This embodiment provides an indole diquinol monomer containing a methyl side group, and the preparation method is as follows:

[0087] 1) In a nitrogen atmosphere, 14.7 g of indoledione (0.1 mol) and 42 g of o-phenyl dimethyl ether (0.3 mol) were added to a 100 mL three-necked flask equipped with a stirrer, 50 ml of sulfuric acid was slowly added under stirring, the mixture was stirred and mixed, the temperature was slowly raised to 120 ° C and heated under reflux for 4 h, the resulting mixed solution was poured into deionized water, filtered, repeatedly washed with deionized water until neutral, and dried to prepare indole diphenyl tetramethyl ether monomer.

[0088] 2) In a nitrogen atmosphere, in a 100 mL three-necked flask equipped with a stirrer, first add 10 g of the product of step 1) (0.0247 mol), 2.1 g of calcium hydride and 20 ml of N,N-dimethylformamide solvent, stir and mix, slowly heat to 100 ° C, heat under reflux for 1 h, then cool to room temperature, add 4 g of iodomethane (0.05 mol), slowly heat to 100 ° C, heat under reflux for 25 h, pour the resulting mixed solution into deionized water, filter, repeatedly wash with deionized water until neutral, and dry to prepare an indole diphenyl tetramethyl ether monomer containing a methyl side group.

[0089] 3) Under ice bath conditions, 8.38 g of the product (0.02 mol) of step 2) was added to a reaction vessel equipped with a stirrer and a condenser, 90 ml of dichloromethane solvent was slowly added under stirring, and 75 g of boron bromide (0.3 mol) was slowly added through a water separator. After reacting for 12 h, deionized water was added to quench the reaction. The resulting mixed solution was poured into deionized water, filtered, repeatedly washed with deionized water until neutral, and dried to prepare an indole diquinone monomer containing a methyl side group.

[0090] The infrared spectrum and nuclear magnetic resonance spectrum of the indole diquinol monomer containing methyl side groups prepared in this example are as follows: Figure 4 and Figure 5 shown.

[0091] Example 4

[0092] This embodiment provides a self-microporous polymer having an indole spiro ring structure and containing a methyl side group, and the preparation method is as follows:

[0093] In a nitrogen atmosphere, in a 100 mL three-necked flask with a stirring rod, the indole diquinol monomer containing methyl side groups prepared in Example 3, an equal molar amount of tetrafluoroterephthalonitrile and 3 times the molar amount of potassium carbonate were first added, and then 4 times the total mass of N, N-dimethylacetamide solvent and 3 times the mass of N, N-dimethylacetamide solvent were added toluene solvent, stirred and mixed, heated under reflux at 130 ° C for 7 hours, and the obtained material was slowly poured into methanol for precipitation, and then boiled, filtered and dried to obtain a self-microporous polymer with an indole spiro ring structure containing methyl side groups, whose number average molecular weight was 71,000.

[0094] The infrared spectrum of the self-microporous polymer with indole spiro ring structure containing methyl side groups prepared in this example is as follows: Figure 6 shown.

[0095] Comparative Example 1

[0096] Compound I and compound II were reacted at a molar ratio of 1:1 at 160°C, using N-methylpyrrolidone (NMP) as a solvent and potassium carbonate as an acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerized microporous polymer; the reaction formula is as follows:

[0097]

[0098] The self-microporous polymer films made of the self-microporous polymers prepared in Example 2, Example 4 and Comparative Example 1 were subjected to gas separation tests.

[0099] The preparation process of the self-microporous polymer film is as follows: the self-microporous polymer is dissolved in N,N-dimethylacetamide solvent to prepare a dilute solution with a mass concentration of 3-5%, and the insoluble matter is filtered through a 0.45μm Teflon filter to obtain a uniform self-microporous polymer solution. The solution is evenly coated on a clean 9cm×9cm glass plate with a scraper, placed in an oven at 70°C for 12 hours, and cooled naturally. The obtained self-microporous polymer film is immersed in an inert organic solvent to eliminate the thermal history in the film, and then the obtained film is placed in a vacuum oven at 100°C for drying to obtain a self-microporous polymer film with a size of 9cm×9cm and a thickness of about 60-120μm.

[0100] A gas permeameter was used, and the specific method is as follows: the gas permeability properties of the microporous polymer film were tested using the differential pressure method (constant volume variable pressure method). During the test, the test film was cut to a suitable size, placed in the test cell, and sealed with a sealing ring. The upstream pressure was set to 2atm, and the downstream was evacuated to vacuum. After the downstream pressure stabilized for a period of time, the test was carried out at 25°C. The gas permeability coefficient (P) was used to characterize the separation effect of the polymer film on the gas group, and α represented the selectivity of the ideal gas. The specific results are shown in Table 1.

[0101] Table 1 Gas permeability and selectivity of self-microporous polymer films made of self-microporous polymers prepared in Example 2, Example 4 and Comparative Example 1

[0102]

[0103]

[0104] The permeability coefficients of N2, CH4, O2, CO2 and H2 in Comparative Example 1 are 118.9, 171.7, 403.9, 2667.3 and 1279.8 Barrer, respectively, which are higher than the permeability coefficients of Implementation Example 2 and Implementation Example 4, but the gas separation coefficients of H2 / N2, CO2 / N2, CO2 / CH4 and O2 / N2 in Implementation Example 2 and Implementation Example 4 are much higher than the gas separation coefficient of Comparative Example 1. The H2 / N2, CO2 / N2, CO2 / CH4 and O2 / N2 of Implementation Example 4 are all above the 2008 Robinson upper limit, showing the excellent separation performance of the microporous polymer membrane, while the H2 / N2, CO2 / N2, CO2 / CH4 and O2 / N2 of Implementation Example 2 are near the 2008 Robinson upper limit.

[0105] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An indole diquinol monomer containing different side groups, characterized in that: The structural formula is shown in Formula Ⅰ; In formula I, R is -CH3 or -Ph-C(CH3)3.

2. A method for preparing the indole diquinol monomer containing different side groups according to claim 1, characterized in that: The following steps are involved: Step 1, subjecting indoledione and o-phthalic acid to a Friedel-Crafts acylation reaction to obtain an indole diphenyl tetramethyl ether monomer; Step 2, subjecting the indole diphenyl tetramethyl ether monomer to an N-alkyl substitution reaction with a halogenated compound under the catalysis of an alkali metal or alkali metal salt catalyst to obtain an indole diphenyl tetramethyl ether monomer containing different side groups; Step 3, subjecting the indole diphenyl tetramethyl ether monomer containing different side groups to a Lewis acid catalyst for a Lewis acid-catalyzed reaction to obtain the indole diphenyl tetramethyl ether monomer containing different side groups; The halogenated compound is one of p-fluorobenzonitrile, p-chlorobenzonitrile, methyl iodide and tert-butyl bromobenzene.

3. The method for preparing indole diquinol monomers containing different side groups according to claim 2, characterized in that: In step 1, the molar ratio of the indoledione to the o-phthalic acid dimethyl ether is 1:3; the temperature of the Friedel-Crafts acylation reaction is 110-120° C., and the time is 4-5 hours.

4. The method for preparing indole diquinol monomers containing different side groups according to claim 2, characterized in that: In step 2, the molar ratio of the indole diphenyl tetramethyl ether monomer to the halogenated compound is 1:(1-2.5); the alkali metal or alkali metal salt catalyst is one of potassium carbonate, cesium carbonate or calcium hydride; the temperature of the N-alkyl substitution reaction is 100-120° C., and the time is 14-30 hours.

5. The method for preparing indole diquinol monomers containing different side groups according to claim 2, characterized in that: In step 3, the molar ratio of the indole diphenyl tetramethyl ether monomer containing different side groups to the Lewis acid catalyst is 1:(10-15); the Lewis acid catalyst is boron bromide or aluminum trichloride; the temperature of the Lewis acid catalytic reaction is 0°C and the time is 10h-24h.

6. Use of the indole diquinol monomer containing different side groups as claimed in claim 1 in the preparation of self-microporous polymers or membrane separation.

7. A self-microporous polymer, characterized in that: The structural formula is shown in Formula II; In formula II, R is -CH3 or -Ph-C(CH3)3; n is the degree of polymerization, and n is an integer from 1 to 100.

8. A method for preparing a self-microporous polymer according to claim 7, characterized in that: The following steps are involved: The indole diquinol monomer containing different side groups as claimed in claim 1 is mixed with tetrafluoroterephthalonitrile, a base catalyst, a solvent and a water-carrying agent to obtain the self-microporous polymer.

9. The method for preparing a self-microporous polymer according to claim 8, characterized in that: The molar ratio of the indole diphenyl tetraol monomer containing different side groups to tetrafluoroterephthalonitrile and the base catalyst is 1:1:3; the reaction temperature is 130-200°C and the reaction time is 4-30 hours; the solvent is a non-protonic polar solvent; and the water-carrying agent is at least one of benzene, toluene, xylene and chlorobenzene.

10. A gas separation membrane, characterized in that: The raw material comprises the self-microporous polymer as claimed in claim 7.

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